Vishal Kothari

The Long Non-Coding RNA PCAT-1 Promotes Prostate Cancer Cell Proliferation through cMyc

Long non-coding RNAs (lncRNAs) represent an emerging layer of cancer biology, contributing to tumor proliferation, invasion, and metastasis. Here, we describe a role for the oncogenic lncRNA PCAT-1 in prostate cancer proliferation through cMyc. We find that PCAT-1–mediated proliferation is dependent on cMyc protein stabilization, and using expression profiling, we observed that cMyc is required for a subset of PCAT-1–induced expression changes. The PCAT-1–cMyc relationship is mediated through the post-transcriptional activity of the MYC 3′ untranslated region, and we characterize a role for PCAT-1 in the disruption of MYC-targeting microRNAs. To further elucidate a role for post-transcriptional regulation, we demonstrate that targeting PCAT-1 with miR-3667-3p, which does not target MYC, is able to reverse the stabilization of cMyc by PCAT-1. This work establishes a basis for the oncogenic role of PCAT-1 in cancer cell proliferation and is the first study to implicate lncRNAs in the regulation of cMyc in prostate cancer.

Maternal Embryonic Leucine Zipper Kinase (MELK) as a Novel Mediator and Biomarker of Radioresistance in Human Breast Cancer

Purpose: While effective targeted therapies exist for estrogen receptor–positive and HER2-positive breast cancer, no such effective therapies exist for triple-negative breast cancer (TNBC); thus, it is clear that additional targets for radiosensitization and treatment are critically needed. Experimental Design: Expression microarrays, qRT-PCR, and Western blotting were used to assess MELK RNA and protein expression levels. Clonogenic survival assays were used to quantitate the radiosensitivity of cell lines at baseline and after MELK inhibition. The effect of MELK knockdown on DNA damage repair kinetics was determined using γH2AX staining. The in vivo effect of MELK knockdown on radiosensitivity was performed using mouse xenograft models. Kaplan–Meier analysis was used to estimate local control and survival information, and a Cox proportional hazards model was constructed to identify potential factors impacting local recurrence-free survival. Results: MELK expression is significantly elevated in breast cancer tissues compared with normal tissue as well as in TNBC compared with non-TNBC. MELK RNA and protein expression is significantly correlated with radioresistance in breast cancer cell lines. Inhibition of MELK (genetically and pharmacologically) induces radiation sensitivity in vitro and significantly delayed tumor growth in vivo in multiple models. Kaplan–Meier survival and multivariable analyses identify increasing MELK expression as being the strongest predictor of radioresistance and increased local recurrence in multiple independent datasets. Conclusions: Here, we identify MELK as a potential biomarker of radioresistance and target for radiosensitization in TNBC. Our results support the rationale for developing clinical strategies to inhibit MELK as a novel target in TNBC. Clin Cancer Res; 22(23); 5864–75. ©2016 AACR.

Hypoglycemic agents and potential anti-inflammatory activity

Current literature shows an association of diabetes and secondary complications with chronic inflammation. Evidence of these immunological changes include altered levels of cytokines and chemokines, changes in the numbers and activation states of various leukocyte populations, apoptosis, and fibrosis during diabetes. Therefore, treatment of diabetes and its complications may include pharmacological strategies to reduce inflammation. Apart from anti-inflammatory drugs, various hypoglycemic agents have also been found to reduce inflammation that could contribute to improved outcomes. Extensive studies have been carried out with thiazolidinediones (peroxisome proliferator-activated receptor-γ agonist), dipeptidyl peptidase-4 inhibitors, and metformin (AMP-activated protein kinase activator) with each of these classes of compounds showing moderate-to-strong anti-inflammatory action. Sulfonylureas and alpha glucosidase inhibitors appeared to exert modest effects, while the injectable agents, insulin and glucagon-like peptide-1 receptor agonists, may improve secondary complications due to their anti-inflammatory potential. Currently, there is a lack of clinical data on anti-inflammatory effects of sodium–glucose cotransporter type 2 inhibitors. Nevertheless, for all these glucose-lowering agents, it is essential to distinguish between anti-inflammatory effects resulting from better glucose control and effects related to intrinsic anti-inflammatory actions of the pharmacological class of compounds.

Hiatal hernia repair with biologic mesh reinforcement reduces recurrence rate in small hiatal hernias

The utility of mesh reinforcement for small hiatal hernia found especially during antireflux surgery is unknown. Initial reports for the use of biological mesh for crural reinforcement during repair for defects greater than 5 cm have been shown to decrease recurrence rates. This study compares patients with small hiatal hernias who underwent onlay biologic mesh buttress repair versus those with suture cruroplasty alone. This is a single-institution retrospective review of all patients undergoing repair of hiatal hernia measuring 1-5 cm between 2002 and 2009. The patients were evaluated based on surgical repair: one group undergoing crural reinforcement with onlay biologic mesh and other group with suture cruroplasty only. Seventy patients with hiatal hernia measuring 1-5 cm were identified. Thirty-eight patients had hernia repair with biologic mesh, and 32 patients had repair with suture cruroplasty only. Recurrence rate at 1 year was 16% (5/32) in patients who had suture cruroplasty only and 0% (0/38) in the group with crural reinforcement with absorbable mesh (statistically significant, P = 0.017). Suture cruroplasty alone appears to be inadequate for hiatal hernias measuring 1-5 cm with significant recurrence rate and failure of antireflux surgery. Crural reinforcement with absorbable mesh may reduce hiatal hernia recurrence rate in small hiatal hernias.

Impact on Perioperative Outcomes of Concomitant Hiatal Hernia Repair with Laparoscopic Gastric Bypass

BackgroundThe role of laparoscopic hiatal hernia repair (LHHR) at the time of laparoscopic Roux-en-y gastric bypass (LRYGB) is still debatable. This study aims to assess the safety of concomitant LHHR with LRYGB.MethodsThis study is a multi-center, retrospective analysis of a large administrative database. The University Health System Consortium (UHC) is a group of 112 academic medical centers and 256 of their affiliated hospitals. The UHC database was queried using International Classification of Diseases—9 codes and main outcome measures were analyzed.ResultsFrom October 2006 to January 2010, we found 33,717 patients who underwent LRYGB and did not have a hiatal hernia. In this same time period, 644 patients underwent concomitant LRYGB and LHHR, while 1,589 patients underwent LRYGB without repair of their hiatal hernias. On comparison of patients undergoing LRYGB with simultaneous LHHR with those who underwent LRYGB without a diagnosis of HH, there was no significant difference in mortality, morbidity, length of stay (LOS), 30-day readmission, or cost shown. On comparison of patients with HH who underwent LRYGB and simultaneous LHHR with those who had LRYGB without LHHR, no significant difference with regards to all the outcome measures was also shown.ConclusionsIn conclusion, concomitant hiatal hernia repair with LRYGB appears to be safe and feasible. These patients did not have any significant differences in morbidity, mortality, LOS, readmission rate, or cost. Randomized controlled studies should further look into the benefit of hiatal hernia repair in regards to reflux symptoms and weight loss for LRYGB patients.

Evolution of Laparoscopic Adjustable Gastric Banding

This article reviews the use of laparoscopic adjustable gastric banding in the United States today. It comments on the history of the procedure as well as technical aspects of the operation. Short-term and long-term outcomes of the procedure are examined, and the advantages and disadvantages of this procedure in comparison with the laparoscopic gastric bypass are discussed.

High fat diet induces brain insulin resistance and cognitive impairment in mice.

High fat diet-induced obesity is associated with insulin resistance (IR) and other chronic, diet related illnesses, including dementia. Alzheimer disease is the most common form of dementia, and is characterized by the presence of amyloid plaques and neurofibrillary tangles in brain. This study was designed to determine whether diet-induced changes in peripheral insulin sensitivity could contribute to alterations in brain insulin signaling and cognitive functions. Six week old, male C57BL/6NHsd mice were randomly assigned a high fat diet (40% energy from fat) with 42g/L liquid sugar (HFS) added to the drinking water or a normal chow diet (12% energy from fat) for 14weeks. Metabolic phenotypes were characterized for energy expenditure, physical activity, and food intake, and glucose and insulin tolerance tests. In addition, we examined the changes in protein expression related to brain insulin signaling and cognitive function. Mice fed HFS exhibited a statistically significant increase in obesity, and lower glucose and insulin tolerance as compared to animals fed the normal chow diet. In brain, HFS elicited IR as evidenced by a significant decrease in tyrosine phosphorylation of insulin receptor and an increase serine phosphorylation of IRS-1. These changes were accompanied by inflammatory (NFκB, JNK) and stress responses (p38 MAPK, CHOP) in whole brain lysate. In addition, HFS mouse brain exhibited biochemical changes related to increased amyloid beta deposition and neurofibrillary tangle formation, and decreased synaptic plasticity. These results suggested changes in insulin sensitivity might contribute to cognitive impairment associated with the HFS diet in mice.

The Landscape of Prognostic Outlier Genes in High-Risk Prostate Cancer

Purpose: There is a clear need to improve risk stratification and to identify novel therapeutic targets in aggressive prostate cancer. The goal of this study was to investigate genes with outlier expression with prognostic association in high-risk prostate cancer patients as potential biomarkers and drug targets. Experimental Design: We interrogated microarray gene expression data from prostatectomy samples from 545 high-risk prostate cancer patients with long-term follow-up (mean 13.4 years). Three independent clinical datasets totaling an additional 545 patients were used for validation. Novel prognostic outlier genes were interrogated for impact on oncogenic phenotypes in vitro using siRNA-based knockdown. Association with clinical outcomes and comparison with existing prognostic instruments was assessed with multivariable models using a prognostic outlier score. Results: Analysis of the discovery cohort identified 20 prognostic outlier genes. Three top prognostic outlier genes were novel prostate cancer genes; NVL, SMC4, or SQLE knockdown reduced migration and/or invasion and outlier expression was significantly associated with poor prognosis. Increased prognostic outlier score was significantly associated with poor prognosis independent of standard clinicopathologic variables. Finally, the prognostic outlier score prognostic association is independent of, and adds to existing genomic and clinical tools for prognostication in prostate cancer (Decipher, the cell-cycle progression signature, and CAPRA-S). Conclusions: To our knowledge, this study represents the first unbiased high-throughput investigation of prognostic outlier genes in prostate cancer and demonstrates the potential biomarker and therapeutic importance of this previously unstudied class of cancer genes. Clin Cancer Res; 22(7); 1777–86. ©2015 AACR.

Patient-Level DNA Damage and Repair Pathway Profiles and Prognosis After Prostatectomy for High-Risk Prostate Cancer.

IMPORTANCE A substantial number of patients diagnosed with high-risk prostate cancer are at risk for metastatic progression after primary treatment. Better biomarkers are needed to identify patients at the highest risk to guide therapy intensification. OBJECTIVE To create a DNA damage and repair (DDR) pathway profiling method for use as a prognostic signature biomarker in high-risk prostate cancer. DESIGN, SETTING, AND PARTICIPANTS A cohort of 1090 patients with high-risk prostate cancer who underwent prostatectomy and were treated at 3 different academic institutions were divided into a training cohort (n = 545) and 3 pooled validation cohorts (n = 232, 130, and 183) assembled for case-control or case-cohort studies. Profiling of 9 DDR pathways using 17 gene sets for GSEA (Gene Set Enrichment Analysis) of high-density microarray gene expression data from formalin-fixed paraffin-embedded prostatectomy samples with median 10.3 years follow-up was performed. Prognostic signature development from DDR pathway profiles was studied, and DDR pathway gene mutation in published cohorts was analyzed. MAIN OUTCOMES AND MEASURES Biochemical recurrence-free, metastasis-free, and overall survival. RESULTS Across the training cohort and pooled validation cohorts, 1090 men were studied; mean (SD) age at diagnosis was 65.3 (6.4) years. We found that there are distinct clusters of DDR pathways within the cohort, and DDR pathway enrichment is only weakly correlated with clinical variables such as age (Spearman ρ [ρ], range, -0.07 to 0.24), Gleason score (ρ, range, 0.03 to 0.20), prostate-specific antigen level (ρ, range, -0.07 to 0.10), while 13 of 17 DDR gene sets are strongly correlated with androgen receptor pathway enrichment (ρ, range, 0.33 to 0.82). In published cohorts, DDR pathway genes are rarely mutated. A DDR pathway profile prognostic signature built in the training cohort was significantly associated with biochemical recurrence-free, metastasis-free, and overall survival in the pooled validation cohorts independent of standard clinicopathological variables. The prognostic performance of the signature for metastasis-free survival appears to be stronger in the younger patients (HR, 1.67; 95% CI, 1.12-2.50) than in the older patients (HR, 0.77; 95% CI, 0.29-2.07) on multivariate Cox analysis. CONCLUSIONS AND RELEVANCE DNA damage and repair pathway profiling revealed patient-level variations and the DDR pathways are rarely affected by mutation. A DDR pathway signature showed strong prognostic performance with the long-term outcomes of metastasis-free and overall survival that may be useful for risk stratification of high-risk prostate cancer patients.

MDM2 Inhibition Sensitizes Prostate Cancer Cells to Androgen Ablation and Radiotherapy in a p53-Dependent Manner

PURPOSE: Increased murine double minute 2 (MDM2) expression, independent of p53 status, is associated with increased cancer-specific mortality for men with prostate cancer treated with radiotherapy. We assessed MI-219, a small molecule inhibitor of MDM2 with improved pharmacokinetics over nutlin-3, for sensitization of prostate cancer cells to radiotherapy and androgen deprivation therapy, a standard treatment option for men with high-risk prostate cancer. EXPERIMENTAL DESIGN: The effect of MDM2 inhibition by MI-219 was assessed in vitro and in vivo with mouse xenograft models across multiple prostate cancer cell lines containing varying p53 functional status. RESULTS: MDM2 inhibition by MI-219 resulted in dose- and time-dependent p53 activation and decreased clonogenic cell survival after radiation in a p53-dependent manner. Mechanistically, radiosensitization following inhibition of MDM2 was largely the result of p53-dependent increases in apoptosis and DNA damage as evidenced by Annexin V flow cytometry and γ-H2AX foci immunofluorescence. Similarly, treatment with MI-219 enhanced response to antiandrogen therapy via a p53-dependent increase in apoptotic cell death. Lastly, triple therapy with radiation, androgen deprivation therapy, and MI-219 decreased xenograft tumor growth compared with any single- or double-agent treatment. CONCLUSION: MDM2 inhibition with MI-219 results in p53-dependent sensitization of prostate cancer cells to radiation, antiandrogen therapy, and the combination. These findings support MDM2 small molecule inhibitor therapy as a therapy intensification strategy to improve clinical outcomes in high-risk localized prostate cancer. TRANSLATIONAL RELEVANCE: The combination of radiotherapy and androgen deprivation therapy is a standard treatment option for men with high-risk prostate cancer. Despite improvements in outcomes when androgen deprivation therapy is added to radiation, men with high-risk prostate cancer have significant risk for disease recurrence, progression, and even death within the first 10 years following treatment. We demonstrate that treatment with MI-219 (an inhibitor of MDM2) results in prostate cancer cell sensitization to radiation and androgen deprivation therapy in vitro and in vivo. Triple therapy with MI-219, radiation, and androgen deprivation therapy dramatically decreased tumor growth compared with any single- or double-agent therapy. These findings provide evidence that inhibition of MDM2 is a viable means by which to enhance the efficacy of both radiation and androgen deprivation therapy and thereby improve outcomes in the treatment of prostate cancer. As such, further investigation is warranted to translate these findings to the clinical setting.